Datasheet

AD7398/AD7399
Rev. C | Page 18 of 24
APPLICATIONS INFORMATION
STAIRCASE WINDOWS COMPARATOR
Many applications need to determine whether voltage levels are
within predetermined limits. Some requirements are for
nonoverlapping windows and others for overlapping windows.
Both circuit configurations are shown in Figure 33 and
Figure 34, respectively.
02179-033
AD8564
10kΩ
+
–
+
–
WINDOW 1
V+
10kΩ
+
–
+
–
WINDOW 2
V+
AD8564
10kΩ
+
–
+
–
WINDOW 3
V+
10kΩ
+
–
+
–
WINDOW 4
V+
1/2
AD8564
10kΩ
+
–
+
–
WINDOW 5
V+
V
TEST
V
REF
AD7398/
AD7399
GND
V
DD
V
OUT
AV
REF
A
V
OUT
BV
REF
B
V
OUT
CV
REF
C
V
OUT
DV
REF
D
Figure 33. Nonoverlapping Windows Comparator
02179-034
V
REF
V
OUT
A
V
OUT
B
V
OUT
C
V
OUT
D
GND
WINDOW 2
WINDOW 1
WINDOW 3
WINDOW 4
WINDOW 5
Figure 34. Nonoverlapping Windows Range
02179-035
AD8564
10kΩ
+
–
+
–
WINDOW 1
V+
10kΩ
+
–
+
–
WINDOW 2
V+
1/2
AD8564
10kΩ
+
–
+
–
WINDOW 3
V+
V
TEST
V
REF
AD7398/
AD7399
GND
V
DD
V
OUT
A
V
REF
A
V
OUT
B
V
REF
B
V
OUT
CV
REF
C
V
OUT
D
V
REF
D
Figure 35. Overlapping Windows Comparator
02179-036
V
REF
V
OUT
A
V
OUT
B
V
OUT
C
V
OUT
D
GND
WINDOW 1
WINDOW 2
WINDOW 3
Figure 36. Overlapping Windows Range
The nonoverlapping circuit employs one AD7398/AD7399 and
ten comparators to achieve five voltage windows. These windows
range between V
REF
and analog ground as shown in Figure 34.
Similarly, the overlapping circuit employs six comparators to
achieve three overlapping windows (see Figure 36).